1. Field of the Invention
This invention relates to polyamides. In one aspect, the invention relates to a process for manufacturing polyamides from .alpha.,.omega.diamine and an .alpha.,.omega.-diamide while in another aspect the inventon relates to a process utilizing urea, thiourea or derivatives of urea and thiourea as a catalyst. In still another aspect, the invention relates to a process for manufacturing nylon-6,6 from hexamethylenediamine and adipamide utilizing a catalyst system comprising urea, thiourea or derivatives of urea and thiourea as catalyst.
2. Description of the Prior Art
It is known in the art that commercially available nylons may be prepared by polymerization of various monomers and combinations of monomers. For example, various nylons may be prepared from the polymerzation of diamines with dicarboxylic acids, the polymerization of dinitriles with diamines in the presence of water, the polymerization of aminonitriles in the presence of water, or the polymerization of lactams.
In part, the instant invention deals with nylons resulting from the polymerization from diamines and diamides. Very few references suggest the polymerization of these two monomer types. For example. U.S. Pat. No. 3,900,450 teaches a process for polymerizing amino acids, diamines, dibasic carboxylic acids and other amide forming derivatives in which diamides are specifically included.
In part, the instant invention relates to the use of ureas and thioureas as a polymerization catalyst for diamines and diamides. Recently, Curatolo et al., U.S. Pat. No. 4,543,407 disclosed a process for polymerizing diamines and diamides utilizing an oxygenated phosphorus compound as a catalyst.
Lastly, the instant invention relates to the production of nylon-6,6 from hexamethylenediamine and adipamide. Commercially, nylon-6,6 is produced from hexamethylenediamine and adipic acid. The present invention offers an alternative to the adipic acid route in preparing this most useful polymer.